Countercurrent chromatography (CCC) is a liquid-liquid partition chromatography method. The partitioning process takes place in an open column space which is free of any solid support matrix, and the method avoids the considerable adsorptive sample loss and tailing of solute peaks which may occur when a solid support matrix is present. Consequently, the method usually yields symmetrical solute peaks in isocratic elution, where peak width naturally increases with the retention time.
Countercurrent chromatographic theory, as well as apparatus for carrying out the method, is described in Y. Ito, Principle and Instrumentation of Countercurrent Chromatography, in Countercurrent Chromatography: Theory and Practice 79-442 (N. B. Mandava and Y. Ito eds. 1988); and in W. D. Conway, Countercurrent Chromatography: Apparatus, Theory and Applications (1990). See also, Ito et al., 49 Anal. Biochem. 1-8 (1972), and U.S. Pat. No. 4,753,734.
A disadvantage associated with CCC is the increased peak width associated with increased retention time of the solute. This increased peak width makes detection of the solute more difficult, and requires a larger volume of eluate to be collected and processed in order to obtain a maximum yield of solute. Nevertheless, increased retention time is desirable in order to avoid coeluting impurities with the solute.
While sharp elution peaks have been noted with CCC, there has been no description or suggestion in the art of a method for obtaining a sharp elution peak while maintaining increased retention time, in the countercurrent chromatography of a solute. See H. J. Cahnmann et al., 538 J. Chromatog. 165-167 (1991).